Return the rc keys and get your money back. Aftermarket keys are half a myth, they will crank you up higher than stock keys, but the acceptable alignment camber/caster is all the same. Once you go past that number you're eating your tires. So while the aftermarket keys will go higher, you're still limited by your alignment. The stock keys will get you to the max lift permitted by your alignment.
Performance accessories makes the best body lifts. The cheaper kits lack necessary parts that the performance accessories kit comes with. There are a lot of things that need to be extended with that body lift. Certain accessories in the engine bay, the steering linkage, the shift lever for the 4x4, the gas tank, all need to be extended with the lift. Don't let people on here fool you into thinking it's easy, it's not. My local shop who never treats me unfairly told me it'd be 750 dollars to install it and that was being nice. I was floored. Suspension connection has the best deals I've seen on body lifts. So save yourself a buck or two versus other sites. Beyond that, the only way to save some coin is to find a friend that loves you and is willing to help you tackle the all weekend job it will be in your garage for no more payment than dinner and plenty of beer. Other than that, expect to shell out at a shop.
Yes, you can put blocks on your rear leafs no problem. Rear blocks are the easiest thing to do out of all this. Order high quality cast blocks and u-bolts from somewhere reputable like 4wheelparts. Do not, I repeat, do not buy aluminum junk from ebay, amazon or parts stores like autozone/pep/oreilly. They crush easily and will end in a nightmare. Look up cheap lift block failure stories.